10 Real Reasons These Actors Were Cast In Major Movie Roles

3. Charlie Day's Rat Monologue From It's Always Sunny Impressed Guillermo Del Toro - Pacific Rim

Charlie Day memorably plays the part of Dr. Newton "Newt" Geiszler in Guillermo del Toro's barmy monster movie Pacific Rim, an eccentric Kaiju expert who spends most of his screen time exchanging ridiculous banter with his pal and colleague Hermann Gottlieb (Burn Gorman).

It's perhaps not terribly surprising to learn that del Toro cast Day in the role of Newt after watching him act in It's Always Sunny In Philadelphia, especially as del Toro himself appeared in an episode of the show the year before Pacific Rim was released. But the single scene which won Day the part is a little more unexpected.

Del Toro chose Day after watching the season six episode "Charlie Kelly: King of the Rats," which opens with a haunted Charlie explaining that he just slaughtered a nest of 200 rats, while pondering the ethical implications of his act. It's this minute-long monologue which convinced del Toro to cast Day:

"He comes out with a stick, and he has a monologue about what it is to hunt the rats in the basement. It was very funny, but he was coming from character. He was not doing big stuff, he was, like, really mourning and lamenting his job, you know, how inhuman it is. And I thought, 'This guy is great at shading and comedy.' There are moments in the movie where he delivers them both."